Corrosion inhibitor composition



United States Patent 3,382,179 CORROSION INHIBITOR COMPOSITION Bill R.Keeney and John A. Knox, Duncan, Okla, assignors to Halliburton Company,Duncan, Okla, a corporation of Delaware No Drawing. Filed Sept. 7, 1965,Ser. No. 485,525 6 Claims. (Cl. 252-148) ABSTRACT OF THE DISCLOSURE Ametal corrosion inhibitor for use with aqueous acids, comprisingspecified amounts of an acetylenic alcohol or sulfide, an amine ornitrogen base compound, and an oxyalkylated naphthenic acid andoptionally a solubilizer or diluent.

The present invention relates to inhibition of corrosion and especiallyto new and useful compositions which may be employed in acid solutionsto decrease or inhibit the corrosion of metal in contact with the acidsolutions.

The present invention is particularly useful in the acidizing ortreating of earth formations and wells traversed by a bore hole.

Many various types and compositions have been employed for theinhibition of corrosion of metal surfaces. Most have been employed withvarying degrees of success. A particular failing of most prior artcorrosion inhibiting compositions is that they cease to be effectiveafter relatively short periods of time or break down under hightemperature conditions, that is temperature of 175 F. or higher.

It is therefore a primary object of the present invention to provide anew and improved composition for inhibiting the corrosion of metalsurfaces in contact with acid solutions, which is effective forrelatively long periods of time and at relatively high temperatures.

Another object of the present invention is to provide a corrosioninhibiting composition which is effective in acid solutions at both lowand high temperatures.

Another object of the present invention is to provide a new improvedcomposition which may be added to acids, especially hydrochloric acidwhich will substantially inhibit the corrosion effect of the acids onmetal surfaces, especially on steel and other ferrous metals, in contactwiththe acids.

Still another object of the present invention is to provide a new andimproved corrosion inhibiting composition which may be employed inacidizing solutions used in well treating and which will efi'ectivelyinhibit the corrosive action of the acid on underground well equipment.

Other objects and advantages of the present invention will becomereadily apparent from a reading of the description of the inventionhereinafter.

It has been discovered that a synergistic blend of an acetylenic alcoholor alcohols, an amine or nitrogen compound, and an ethylene oxidederivative of naphthenic acids in particular amounts of each, provides acomposition having superior corrosion inhibiting properties when addedin small quantities to an acid solution.

In some instances, it may be desired to add a suitable diluent orsolubilizer.

In the preferred form of the invention, two or more acetylenic alcohols,each having an ethynyl hydrogen on the acetylenic group, are employed asthe acetylenic alcohol component.

Some examples of acetylenic alcohols or compounds 3,382,179 Patented May7, 1968 which may be employed in the present invention are:

wherein R is hydrogen, alkyl, phenyl, substituted phenyl or hydroxyalkylradical, and the alpha Rs may be joined together to form a cyclohexylring.

Acetylenic sulfides having the general formula HCECRSRCECH can also beemployed in the present invention. Examples of these are dipropargylsulfide, bis (l-methyl-2propynyl) sulfide and bis (2-ethynyl-2-propyl)sulfide.

The nitrogen or ammonia base compounds that can be employed inaccordance with the present invention are those amines such as mono, diand trialkyl amines having from 2 to 6 carbon atoms in each alkyl moietyas well as the 6 membered N-heterocyclic amines, for example alkylpyridines and mixtures thereof. This includes such amines as ethylamine,diethylamine, triethylamine, propylamine, dipropylamine, tripropylamine,mono, di and tributylamine, mono, di and tripentylamine, mono, di andtrihexylamine and isomers of these such as isopropylamine,tertiarylbutylamine etc. This also includes alkyl pyridines having from1 to 5 nuclear alkyl substituents per pyridine moiety, said alkylsubstituents having from 1 to 12 carbon atoms and preferably thosehaving an average of 6 carbon atoms per pyridine moiety, such as amixture of highboiling tertiary-nitrogen-heterocyclic compounds such asAlkyl Pyridine HB, Reilly HAP (High Alkyl Pyridines) or Reilly 10-20base.

Ethylene oxide derivatives of naphthenic acids suitable for use can varyfrom 12% to 60% by volume of the inhibitor blend and can vary incomposition in the following manner: Ethylene oxide Naphthenic acids(percent by weight):

(percent by weight) Mixed ethylene oxide-propylene oxide derivatives ofnaphthenic acids are also suitable.

Naphthenic acids may be defined as monobasic carboxylic acids of thegeneral formula RCOOH, wherein R is a A more specific derivative is:

if ?I-r2-oI-I cr1)..-o(ooHzCin) sort Hie-0112431 12 In the aboveformula, 12:1 to 20 and x=moles of ethylene oxide or propylene oxide andmay vary from about 25%85% by weight. Additionally, propylene oxide andethylene oxide can be reacted with a naphthenic acid at the same time toprovide a mixed ethylene oxide, propylene oxide composition.

Suitable diluents are diacetone alcohol, mesityl oxide, acetone,alcohols (ethanol, isopropanol, N-propanol, etC.), aromatic solvents,other acid soluble organic solvents or Water.

On a basis of a volume of 100%, a preferred composition of the presentinvention is comprised as follows:

Acetylenic compound3l% to 85% by volume Ethylene oxide derivative-12% to60% by volume Nitrogen or ammonia base compound3%9% by volume based onthe active acetylenics present in the blend.

A solubilizer or diluent may be added to the above preferredcompositions in a concentration of about 5 70-50% of the total volume.

Another preferred composition of the present invention, may be expressedby the formula X+ Y+z= 100% wherein X=Acetylenic compound31% to 85% byvolume Y=Oxide derivative of naphthenic acidl2% to 60% by volumeZ=Nitrogen or ammonia base compound--(.03-.09) (X) (A) by volume whereinA percent active ingredients or activity of the acetylenic compound.

An effective composition or preferred blend, especially at hightemperatures, was found to be as follows:

A crude propargyl alcohol with about 75% active ingredients, with theremainder being non-aqueous reaction products resulting from theproduction of propargyl alcohol is particularly preferred. Pure or 100%propargyl alcohol may be used, but it is more expensive than the crudepropargyl alcohol.

Hexynol in lieu of ethyl octynol also gives superior results in theblend.

High Alkyl Pyridines (Reilly HAP) (assumed to be 100%) can besubstituted with a less active percent of alkyl pyridines by increasingthe amount to be added to the blend, while staying within theconcentration range of from 3 to 9% by volume based on the activeacteylenics present in the blend. Other sources of suitable nitrogencompounds can be obtained elsewhere. Reilly 10-20 base and AlkylPyridines HB are examples of other commercial products which can beused.

A number of laboratory tests were conducted wherein the preferred blendof this invention, compound X, was compared with a prior art corrosioninhibitor, compound A, prepared in accordance with the teachings of US.Patent No. 3,107,221 and consisting of 2 parts acetylenic alcohols and 1part Alkyl Pyridines HB, by volume.

Procedure In these tests, the acid solutions were mixed by diluting B.HCl with water to the desired concentrations.

The acid solutions were then titrated with a standard base solution toascertain the exact acid concentration. The various acid solutions wereprepared in advance in sufficient quantities to complete an entireseries of tests With the same batch of acid.

Corrosion coupons of J-SS steel were ordered in sufficient quantities tocomplete a series of tests on the same batch of coupons. The couponswere cleaned as follows: pickled in an uninhibited 10% HCl acid solutionfor 10 minutes, neutralized in a 10% solution of sodium bicarbonate,scrubbed by hand with a fine Wire brush and a detergent containing apumice, rinsed, dipped in acetone to remove the excess water and thendipped in alcohol and allowed to dry. They were then Weighed to thenearest milligram and stored in a desicator until time for use.

Tests were conducted at various temperatures.

The acid solution was poured into glass bottles in sufficient quantityto approximate the specific acid volume-to coupon surface area ratiothat was desired. The quantity of acid used was dependent upon thesurface area of the coupon to be tested. In most of the tests, a 25cc./in. acid volume to coupon surface area ratio was used.

After the desired amount of acid was poured into the bottles, theinhibitor was added with a hypodermic syringe and the resulting solutionwas stirred with a glass rod. The inhibited acid solution was thenplaced in a water bath which had been set at a predetermined temperatureand allowed to preheat for 20 minutes. After which time, the couponswere placed in the preheated inhibited acid solutions. The coupons wereleft in the acid solutions for the specified test time, then removed,neutralized, recleaned, rinsed, dipped in acetone then alcohol, allowedto dry, then reweighed.

The loss in weight in grams was multiplied times a calculated factor toconvert the loss in weight to lbs./ft. /24 hrs. The factor wascalculated as follows:

Example: Test time, 6 hours, Surface Area of Coupon, 4.0 in. then Fortemperatures in excess of 200 F., tests were conducted in hightemperature and pressure autoclaves that were designed and built by theHalliburton Engineering Department. The autoclaves are designed towithstand temperatures up to 600 F. and pressures up to 10,000 psi. Theyhave rotating tables that hold the beakers containing the acid. Thisallows the acid to be agitated throughout the test. The autoclaves areunique in design in that they have an acid discharge valve over eachbeaker of acid. This allows a test to be terminated immediately ratherthan having to wait for the temperature to cool down sufficiently sothat the head can be opened. There are two temperature controls, onemonitors the temperature of the oil in the autoclave and the other thetemperature of the acid solution. The temperature of the acid solutionis recorded on an electric motor driven chart throughout the time of thetest.

The methods used in the high temperature corrosion tests were basicallythe same as the other tests. The only difference was in the acidvolume-to coupon surface area ratio which was approximately cc./in.(excess acid) and the mechanical operations of the autoclaves.

The results of these tests are set forth hereinbelow:

TABLE I.COMPARISON OF BLEND TEMPERATURE Corrosion rates in 1bs./it. l24hrs. Pressure-Atmospheric unless otherwise indicated SX AND A AT VARIOUS1 Terminated. B Pressure-3,000 p.s.l.

NorE.-For temperatures of 200 F. or less, the acid volume-surface arearatio was 25 cc./in. At 250 F. excess acid (80 cc./ln. was used.

TABLE IL-COMPARISON OF BLEND X AND A WITH VARIOUS ADDITIVES Acidvolume/surface area ratio :25 ccJin. Corrosion rates in lbs./Ft. /24hrs. Coupon-L55 steel Con. Test Test Addl- Inhibin Temp., Time,Oorrodent Corr.

tive itor gals/ F. hrs. Rate X 6 200 16 017 X 6 200 16 009 X 6 200 16027 A 6 200 16 063 A 6 200 16 041 A 6 200 16 034 X 2. 0 150 6 009 X 2. 0150 6 014 X 2. 0 150 6 017 A 2. 0 150 6 026 A 2. 0 150 6 032 A 2. 0 1506 022 Z-Cationic non-emulsifier E-Amphoteric surfactant F-Anionienon-emulsifier Remarks Blend X consistently outperformed Blend Aespecially when longer exposure times and lower concentrations ofinhibitor were involved.

Breakdown tests were conducted as follows, and the results recorded inTable HI hereinbelow. A J-SS coupon was placed in a glass jar containinghydrochloric acid inhibited with 6 gal/1000 of the inhibitor to beevaluated. The jar containing the coupon was then placed in a 200 F.water bath and checked periodically for signs of bubbling indicatingthat the inhibitor had broken and hydrogen gas was being evolved. Theacid volume to coupon surface area ratio used in the breakdown test wascc./in.

TABLE III.COMPABJI'SON OF BREAKDOWN TIMES OF BLEND X AND A Breakdowntests Additional tests were conducted using the individual compounds ofthe preferred blend alone, and following the procedure set forth indetail hereinabove for clearly showing the synergistic effect of thepreferred blended composition.

TABLE IV.-COMPARISON OF BLEND X WIT INDIVIDUAL COMPONENTS THEREOF Acidvolume/surface area ratio :25 cc./in. Corrosion Rates in lbs./it. /24hours Acid-15% HCl CouponsN-8O Steel Test Temperature200 F.

Test 'Iime6 hours Concentration Inhibitor in gals/1,000 Corr. Rate AlkylPyridines HB 6 0. 069 Crude propargyl alcohol 6 0. 032 Pure propargylalcohoL 6 0. 027 Ethyl octynol 6 0.011 Blend X 6 0. 000

The inhibitor or inhibitor composition of the present invention isoperable when employed at temperatures as high as 300 F. in various acidconcentrations. The corrosion which does occur is substantially uniformregardless of temperatures from 60 F. up to and in excess of 250 F. Itprovides long term protection at small concentrations of inhibitor. Itis particularly effective on all types of steel and especially on thatused in oil field grade pipe.

Applications in which the inhibitor of :the present invention isparticularly useful include oil-well acidizing solutions, metalpickling, cleaning and polishing baths, boiler cleaning compositions andthe like.

Broadly, the present invention relates to a new and improved corrosioninhibitor or composition for reducing the corrosive effect of acids onferrous metals consisting essentially of an a'cetylenic alcohol oralchols, a nitrogen or ammonia base compound and an ethylene orpropylene I oxide derivative of a naphthenic acid in certain amounts ofeach, to which composition may be added a suitable diluent orsolubilizer.

The corrosion inhibitor compositions of the present invention areparticularly adapted for use in mineral acids, especially hydrochloricacid. It may also be employed in sulfuric, phosphoric and acetic acidsand the like.

The inhibitor is preferably added to the acid in amounts by volume fromabout /2 gallon to 20 gallons per 1000 gallons of acid. The amount ofthe inhibitor required will vary with the temperatures to be encounteredand the strength or concentration of the acid used. A 15% hydrochloricacid is most common for oil well acidizing operations.

The foregoing disclosure and description of the inven tion isillustrative and explanatory thereof and suitable variations may be madeWithin the scope of the appended claims without departing from thespirit of the invention.

We claim:

1. A metal corrosion inhibitor for use with aqueous acids whichcomprises an acetylenic compound having a formula selected from thegroup consisting of:

wherein in (A) and (B) each R represents a member selected from thegroup consisting of hydrogen, alkyl, phenyl, alkyl substituted phenyland hydroxyalkyl radicals wherein each of the above mentioned alkyl andhydroxyalkyl radicals have from 1 to 4 carbon atoms, inclusive, andwherein in (C) each R represents an alkylene radical having from 1 to 4carbon atoms inclusive; an amine selected from the group consisting ofpyridine, lower alkyl pyridines, alkylamines having from 4 to carbonatoms inclusive, in each alkyl substituent, and hydroxy loweralkylamines; an oxyalkylated naphthenic acid having the formula:

wherein R is a naphthenic radical X is selected from the groupconsisting of ethylene oxide, propylene oxide or mixtures thereof, and

n=number of moles of X ranging from about 85% by weight of compound;

wherein the acetylenic compound is present in an amount by volume of31%85%, the amine is present in an amount by volume of 3%9% based on theamount of the active acetylenic compound present and the oxyethylated oroxypropylated naphthenic acid is present in an amount by volume of from12%60%.

2. The corrosion inhibitor compound of claim 1, wherein a diluent isadded in a concentration of from about S%50% of total volume.

3. A corrosion-inhibited mineral acid comprising an aqueous solution ofa mineral acid and from 0.05% to 2.0% by volume of a mixture consistingessentially of from 31% to 85% by volume of an acetylenic compoundhaving a formula selected from the group consisting of:

wherein in (A) and (B) each R represents a member selected from thegroup consisting of hydrogen, alkyl, phenyl, alkyl substituted phenyland hydroxyalkyl radicals wherein each of the above mentioned alkyl andhydroxyalkyl radicals have from 1 to 4 carbon atoms, inclusive, andwherein in (C) each R represents an zalkylene radical having from 1 to 4carbon atoms inclusive; from 3% t0 9% by volume of an amine compound,based on the amount of the acetylenic compound selected from the groupconsisting of pyridine, lower alkyl pyridines, alkylamines having from 4to 10 carbon atoms inclusive, in each alkyl substituent, and hydroxylower alkylamines; and from 12% to 60% by volume of an oxyalkylatednaphthenic acid having the formula:

Ri ]O(X)nH wherein R is a naphthenic radical X is selected from thegroup consisting of ethylene oxide, propylene oxide or mixtures thereof,and

n=number of moles of X ranging from about 25%- by weight of compound.

4. The composition of claim 3, wherein a diluent is added to the mixturein a concentration of from about 5%50% of total volume of the mixture.

5. A metal corrosion inhibitor for use with aqueous acids consistingessentially of propargyl alcohol of about 4.0 parts by volume, ethyloctynol of about 1.5 parts by volume, lower alkyl pyridines of about0.34 part by volume and an oxyethylated naphthenic acid having moles ofethylene oxide ranging from about 25%85% by weight of compound of about1.5 parts by volume.

6. A corrosion-inhibited mineral acid comprising an aqueous solution ofmineral acid containing from 0.05% to 2.0% by volume of a mixtureconsisting of from 3.1 to 8.5 parts by volume of propargyl alcohol, 0.3to 0.9 part by volume of a mixture of lower alkyl pyridines and 1.2 to6.0 parts by volume of an oxyalkylated naphthenic acid having theformula:

5 R- Jo-(X)..H

wherein R is a naphthenic radical X is selected from the groupconsisting of ethylene oxide, propylene oxide or mixtures thereof, and

n=number of moles of X ranging from about 25%- 85% by weight ofcompound.

References Cited UNITED STATES PATENTS 2,614,983 10/1952 Caldwell et al.252-396 X 2,814,593 11/1957 Beiswanger et a1. 2528.55 2,914,557 11/1959Oxford 252392 3,107,221 10/1963 Harrison et al. 252148 3,140,260 7/1964Foster et al. 252 -151 LEON D. ROSDOL, Primary Examiner.

H. B. GUYNN, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,382,179 May 7, 1968 Bill R. Keeney et al.

It is certified that error appears in the above identified patent andthat said Letters Patent are hereby corrected as shown below:

Column 2, line 37, "tertj wlbutylamine should read tertiarybutylamire67, the formula should a plgaear as shown below:

Column 7, line 10, in the benzine ring, "A should read H Signed andsealed this 10th day of March 1970.

est:

Commissioner of Patents

